The invention relates to a device and method for securing the standstill of a motor vehicle with a distance-related longitudinal dynamic control module, which is contained in at least one electronic control unit and by which the motor vehicle is decelerated down to a standstill while maintaining a defined distance from a target object.
With respect to the technological environment reference is made to the German patent document DE 101 52 632 A1, as an example.
Vehicles that exhibit a speed controller with a distance sensing system already exist on the market. In particular, when driving on a highway or an expressway, such a vehicle tries to maintain a presetable travel speed, but reduces this speed when the vehicle approaches a vehicle that is traveling ahead (target object). Such a feature also gives the driver of the vehicle optimum comfort in bumper-to-bumper traffic, because the speed controller with a distance sensing system (for example, an ACC “Active Cruise Control”) always maintains an adequate safety distance from the vehicle traveling ahead. If the vehicle traveling ahead accelerates, then the speed controller with the distance sensing system (hereinafter also referred to as an “ACC system”) also accelerates the vehicle, which is provided with such a distance sensing system, and in particular until the set target speed or the speed of the vehicle traveling ahead (if it is driving more slowly than the target speed) is reached.
In addition to the ACC systems, which are operated predominantly on well-constructed roads in the higher speed range, there are also so-called stop & go systems that make possible a comparable driver assistance in the lower speed range down to as far as a standstill of the vehicle. These systems require not only a powerful close range sensing system, but also an electronically engagable brake system, which is capable of reliably holding the vehicle in the standstill phase and preventing the vehicle from continuing to roll, until the driver of the vehicle or the stop & go system itself has given a commensurate command to go (start command).
The invention improves such distance-related speed control systems with a stop & go function, on the one hand, in terms of comfort and, on the other hand, in terms of a fast response behavior.
According to the invention, a device is provided for securing a standstill of a motor vehicle with a distance-related longitudinal dynamic control module, which is contained in at least one electronic control unit and by which the motor vehicle is decelerated down to a standstill while maintaining a defined distance from a target object. The device is characterized in that at least until reaching the standstill, a nominal brake torque is defined by the longitudinal dynamic control module for a brake control module. At a defined first time after a detected standstill of the motor vehicle, the longitudinal dynamic control module transmits a transfer signal to the brake control module; whereupon independently of the predefinition of a nominal brake torque by the longitudinal dynamic control module, the brake control module alone builds up and/or holds a wheel brake torque in the sense of a parking brake function, and that at a defined second time after a start command, the longitudinal dynamic control module defines again, by itself for the brake control module, a nominal brake torque, starting at the actual brake torque that is on hand at this time, for the purpose of decreasing the wheel brake torque. Advantageous further developments are described and claimed herein.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.